Diagnostic devices incorporating fluidics and methods of manufacture

ABSTRACT

The present invention relates to diagnostic devices incorporating electrode modules and fluidics for performing chemical analyses. The invented devices consist of at least one component sensor formed on an electrode module, the sensor being contained within a fluidic housing. The electrode module is a laminate of a perforated epoxy foil and a photo-formed metal foil with sensor membranes deposited into the perforations. The fluidic housing is a diagnostic card consisting of a plastic card-like body, the at least one component sensor, a sealed chamber defined in the card body for containing a fluid, a fluid conduit for fluidically connecting the chamber with the sensor region, a valve for fluidically connecting the chamber to the fluid conduit, and a delivery structure separate and distinct from the valve for forcing fluid from the chamber and into the fluid conduit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 13/923,845 filed Jun. 21, 2013, which is a divisionalapplication of U.S. patent application Ser. No. 12/870,463 filed Aug.27, 2010, which is a continuation of U.S. patent application Ser. No.10/856,782 filed Jun. 1, 2004 (now U.S. Pat. No. 7,842,234 issued Nov.30, 2010 and entitled Diagnostic Devices Incorporating Fluidics AndMethods Of Manufacture), which is a continuation in part of U.S. patentapplication Ser. No. 10/307,481 filed Dec. 2, 2002 (now U.S. Pat. No.7,094,330 issued Aug. 22, 2006 and entitled Heterogeneous MembraneElectrodes), the contents of all of which are herein incorporated byreference.

FIELD OF THE INVENTION

This invention relates to unit-use diagnostic test cards comprisingsensors and fluidics and to card readers therefor.

BACKGROUND OF THE INVENTION

Plastic cards in the general shape and size of credit cards, but withembedded integrated circuit chips are well known in the art. Suchdevices have appeared as articles of commerce in numerous applicationswhere low cost electronic devices for personal use are required, such asbank cards, phone cards and the like. They are known as smart cards orIC cards. There was no teaching in the prior art concerning the use ofcard systems of this type that have been modified by removal of theintegrated circuit chip and addition of fluidic and sensor elements foruse in chemical analysis or in-vitro diagnostics, prior to the followingpublished disclosures which are related to this invention: ElectrodeModule U.S. Pat. No. 6,896,778, and Point-of-Care In-Vitro BloodAnalysis System U.S. Pat. No. 6,845,327.

In the patent entitled Heterogeneous Membrane Electrodes, U.S. Pat. No.7,094,330, there is disclosed a diagnostic card containing a sensorarray on an electrode module comprising a heterogeneous membranereference electrode and electrochemical indicator electrodes, thedisclosed electrode module being contained in a credit card sizedfluidic housing. This present patent application now disclosesadditional inventive components and inventive elements of an electrodemodule and a diagnostic card incorporating fluidic elements.

Diagnostic test cards and cartridges for chemical analysis are wellknown in the art. Diagnostic cards and cartridges incorporating sensorsand fluidic elements are known in the art. Early examples are U.S. Pat.No. 4,301,412 that discloses a pair of electrodes in a plastic housingwith an orifice for sample introduction and a capillary conduit forsample flow to the electrodes. Similar devices were also disclosed inthe capillary flow technology described in U.S. Pat. No. 5,141,868.Diagnostic card devices with sensors and fluidics also incorporatingon-board fluids contained in sealed housings within the cartridge weredisclosed in U.S. Pat. Nos. 4,436,610 and 4,654,127. The '127 deviceconsisted of a plastic card-like housing with sensors and conduits witha sealed chamber containing a calibrating fluid mounted on the card. Inuse of this device the seal of the fluid-containing chamber was rupturedwhen the user manually turned a chamber element and subsequent fluidpropulsion to the sensors on the card was by gravity. An improveddiagnostic cartridge with sensors, fluid conduits and on-board fluid wasdisclosed in U.S. Pat. No. 5,096,669. This device consisted of a sensorarray on a microfabricated silicon chip in a plastic housing withfluidic conduits, as well as a sealed pouch containing a calibratingfluid. The improvement was that the device was designed so that thefluid containing pouch could be ruptured and calibrating fluid moved tothe sensors by the read-out instrument rather than manually. In the useof this device the sample is collected into the card away from thesensors, then subsequently moved to the sensor location by an instrumentmeans. In both the '127 and '669 patents the fluid seal is made by afoil coated element and its rupture is by a piercing element that ripsthrough the foil. U.S. Pat. No. 5,325,853 discloses a diagnostic devicewith sensors and fluidics with on-board fluid that is not sealedremotely from the sensors.

Of the devices of the prior art only the '669 device has provencommercially useful for the measurement of a broad range of analytes inparallel in sensor panels. The '669 device incorporates many unique andproprietary designs and special purpose components. The manufacturingprocesses also are unique to their devices and specialized assemblyequipment is required. The '669 device and other prior art diagnosticdevices generally require numerous process steps in electrodemanufacture and numerous piece-parts and precision assembly steps in thecard manufacture. Thus, this technology has proven expensive tomanufacture, thereby limiting the broader utilization of the technology.

There are also performance limitations of the '669 technology. The fluidin the foil-lined and sealed reservoir has very limited shelf stabilitybecause the seal lengths are short. Furthermore, the reservoir ispressurized during fabrication and the sealed reservoir is rupturedduring use by piercing the foil reservoir under applied pressure.Therefore the fluid in the reservoir is under pressure and, thus, hasthe potential to be evacuated from the reservoir in an explosive mannercausing a potential for segmented fluid flow. Such problems can reducethe reliability of the '669 device. The sample transfer into the samplecollection area of the '669 device is not done anaerobically. This mayresult in errors when measuring dissolved gases such as oxygen andcarbon dioxide, particularly in samples which have low buffer capacityfor those gases. Furthermore, there is no provision for reliablethermostating of the test fluid adjacent to the sensors.

There is now a need to provide for simpler and more generic designs andmanufacturing procedures for sensor arrays and fluidics indiagnostic-card devices.

SUMMARY OF THE INVENTION

The current patent teaches designs and manufacturing processes torealize fluidic elements in diagnostic cards consisting of low costcomponents and manufacturing processes. This approach leads tosignificantly simpler devices than those of the prior art. There arefewer assembled parts, processes are generic and use generic equipmentperforming low tolerance assembly processes. The result is that devicesaccording to this invention can be manufactured cost-effectively.Furthermore the diagnostic card of this patent incorporates many newinventive features which address performance limitations of prior artdevices.

The invention provides a diagnostic card for use with a card reader insensing at least one component concentration of a fluid sample. Thediagnostic card includes a card body, at least one component sensorlocated in a sensor region in the card body, a sealed chamber defined inthe card body for containing a fluid, preferably remote from the sensorregion, a fluid conduit for fluidically connecting the chamber with thesensor region, a valve for fluidically connecting the chamber to thefluid conduit, and a delivery structure separate and distinct from thevalve for forcing fluid from the chamber and into the fluid conduit,when the chamber contains fluid and is fluidically connected to thefluid conduit. In a preferred embodiment, the chamber is a hermeticallysealed fluid reservoir, preferably in the form of an aluminum foil-linedcavity. The chamber is preferably filled without pressurization so thatthe contents of the sealed chamber are not under pressure when thechamber is connected to the fluid conduit by the valve. Furthermore, thevalve preferably fluidically connects the chamber to the fluid conduitwithout simultaneous pressurization of the fluid in the chamber. Thevalve preferably includes a valve body for rupturing a chamber wall fromwithin the chamber. The valve preferably includes a valve bodydisplaceably received in a valve seat in the card body, the valve bodybeing within the chamber, the valve body and valve seat being shaped andconstructed for pinching and rupturing a wall of the chamber upondisplacement of the valve body relative to the valve seat. The valvebody is preferably a rupture plug and the valve seat is preferably aplug receiving bore in the card body, with the plug and plug receivingbore having cooperating edges for rupturing the chamber wall upondisplacement of the plug in the plug receiving bore.

The invention further provides a sensor array on an electrode moduleincorporated into a credit-card sized plastic card body. The electrodemodule preferably includes a thin slab that is a laminate of an epoxyfoil with a gold coated copper foil. The upper surface of the module isthe epoxy foil which is perforated with holes. The lower surface of themodule includes the gold coated copper foil which has been formed intoan array of at least two electrodes. Each electrode of the arrayincludes a formed element in the shape of a strip which constitutes anelongated electrical path connecting a contact end or contact pad at oneend for connection to an external electrical circuit in a card reader,and a sensor end or sensor region under a hole through the epoxy at itsother end. The module preferably comprises an array of such stripelectrodes, each having a conductor path, a contact end and a sensorend, each sensor end of the array being located at a different hole inthe epoxy foil. A sensor is formed on an electrode of the array when asensor membrane or membranes are deposited into a hole in the epoxy onthe top surface of the module, thus contacting the sensor region of themetal electrode on the bottom surface. In a preferred embodiment, asensor array is made by depositing a different sensing membrane intoeach hole of each electrode sensing region of the electrode array.

The module is sealed to the plastic card body so that its upper epoxysurface including the sensor membranes face a fluidic conduit within thecard body and the lower metalized surface faces outward and is exposedfor external access to the contact pads. The array of holes with sensormembranes, referred to herein as the sensor region, is preferably asubstantially linear region extending along the center of the module,which region aligns to a substantially linear fluidic conduit in theplastic card body so that fluid flowing through the fluidic conduitduring use of the device contacts the sensor membranes of the array inthe sensor region. The portion of the module's epoxy surface not locatedin the sensor region is sealed off by adhesive between the plastic cardbody and the module so that fluids are retained within the conduit atthe sensor region and do not escape to or around the edge of the module.

In a preferred embodiment, the metal layer of the electrode modulefurther includes a metal heater element in a heating region on its lowersurface that is electrically isolated from the sensor electrodes andintended for contact with a first heater block contained in a cardreader. The module's metal heater element is a formed element in theshape of a split ring which substantially surrounds the sensor region ofthe sensor array. The ring is split at one, two or more locations, thatis to say the metal heater element preferably comprises of two or moreshaped metal elements which together form the split ring surrounding thesensor region of the module. Each split represents a connecting gapconnecting the sensing and contacting regions of the module. Eachelectrode of the electrode array now has the conductor path whichconnects the sensor end of the electrode to the contact end passingthrough a connecting gap so that the electrodes of the array areelectrically isolated from the metal of the heater element. Theconductor paths of the electrode array are preferably formed so thatthey are especially long and thin so that heat transport from the sensorregion to the contact region is minimized. In one embodiment, a separateconnecting gap is provided for each conductor path. In another preferredembodiment, the contact ends and connecting gaps are distributed aboutthe sensing region so that all conductor paths are of equal length.

During use, a diagnostic card in accordance with the invention isinserted into the card orifice of a read-out instrument. The card'selectrode module makes electrical contact at each of the contact pads ofthe electrode array to a z-action connector contained within the cardreader. The card's electrode module also makes contact at its metalheater region to a first heater block also contained within the cardreader. The first heater block is coplanar with the card's modulesurface and proximal to it when the card is in the card-reader's cardinsertion orifice. The first heater block makes physical contact to themetal heater region of the module, but also extends to cover the entiresensor region and a substantial region of the electrical paths, in closeproximity but not in physical contact. This allows efficient heattransfer to the paths, but maintains electrical isolation from them.Thus, the first heater block heats the sensing region of the module andthe fluid in the card's fluidic conduit above the sensing region bydirect thermal conduction from the block to the module's metal heaterregion, as well as indirectly through an air gap at the sensor regionand thence to the sensors and fluids, and indirectly through a thin airgap to the electrical paths of the electrode array. This configurationaccomplishes thermal bootstrapping of the electrode paths, which furtherminimizes the heat transport from the sensor region to ambient along thepaths. This configuration thus provides for more uniform temperaturecontrol of the sensor region. A second heater block of the card readeris coplanar with the card's upper surface and proximal to it when thecard is in the card-reader's card insertion orifice. The second heaterblock makes physical contact to the card's upper plastic surface. Thesecond heater block covers the sensor area of the card but extends adistance along the direction of the fluidic channel in both directionsaway from the sensor area. This provides heat to the fluid in thefluidic conduit in the regions immediately upstream of the sensor areaand immediately downstream. This minimizes heat flow from the sensorregion along the fluidic conduit by effectively thermally bootstrappingthe fluid in the conduit. Thus the card's entire sensor area, thefluidic conduit proximal to the sensor area, the sensors' electricalpaths and the fluid in the conduit upstream and downstream of the sensorarea are all contained within a thermostatted cavity comprising heaterblocks above and below. This arrangement allows rapid heating of a coldsample fluid to its control temperature, and also accomplishes veryprecise thermostatting to the control temperature.

In another aspect of the diagnostic card of this invention there isprovided a connector means in the read-out device for connection to thecard's electrode module. The connector means is a z-action connectorcomprising an array of contact elements, being formed metal films on aflex substrate, which flex-substrate is placed on a flexible cantilever,preferably a plastic cantilever. The cantilever is positioned so thatwhen the card is inserted into the card reader's card insertion orificethe module's outer surface with its contact pad array is proximal to thecontact elements of the flex substrate and the cantilever is depressedso as to apply z-action force between the connector array on the flexsubstrate and the contact pad array on the module. Because theelectrical contacting elements are thin metal films on a flex substrate,the invented flex connector drains far less heat than conventionalt-action connector pins used to contact smart cards of the known art.Additionally, the flex substrate and its connector array can alsoincorporate electronic components of card reader's electrical circuitry,resulting in a cost reduction of the card reader.

In still another aspect of the diagnostic card of the invention there isprovided an improved design for the sealed calibrator reservoir. In thepreviously disclosed card of U.S. Pat. No. 7,094,330, the calibratorreservoir comprised a cavity in the card's plastic body, which afterfilling with calibrator fluid was sealed by an overlayer of a metalcoated foil element. We have found improved lifetime of the sealedcalibrator when the cavity in the plastic card body is clad on bothsides with an aluminum foil lamination. The new design comprises adiagnostic card with a sensor array on an electrode module, and a sealedcalibrator fluid reservoir, which when the seal is ruptured during theuse of the device, becomes fluidically connected to the module's sensorregion. The reservoir comprises a cavity in the card body, a firstplastic-film-coated aluminum foil deformed into the cavity so that thefoil contacts the plastic surface of the cavity with its aluminumsurface facing the plastic of the cavity and the foil extends beyond theperimeter of the cavity, a calibrator fluid in the cavity, and a secondplastic-coated aluminum foil element overlaying the first with itsplastic surface facing the plastic surface of the first foil element,and a fused plastic-to-plastic seal between the two foil elements whichhermetically seals the calibrator fluid, the seal being formed in theregion around the perimeter of the cavity. For good room temperaturestability of the calibrator fluid in the sealed reservoir, we havepreferred that the width of the perimeter seal be at least 3 mm alongthe entire perimeter, thus providing a long leakage path for material toescape through the fused plastic seam joining the first and secondmetallized cladding layers.

In another aspect of the improved calibrator fluid reservoir, there isprovided an improved rupture means for automatically rupturing the foilseal upon use of the device, so as to enable the subsequent delivery ofcalibrator fluid to the measurement cell which is the fluidic cavityabove the sensor region of the card's electrode module. In this improvedrupture means there is a plug sealed between the metal foil claddingelements of the calibrator chamber. This plug is caused to move when thecard is inserted into the card reader's card insertion orifice whichmovement causes rupture of the metal foil cladding. A conduitfluidically connects the calibrator reservoir at its point of rupture tothe measurement cell, enabling displacement of calibrator fluid to themeasurement cell after rupture of the seal.

In another aspect of the diagnostic card of the invention there isprovided an improved design for the sample entry port. An adhesivegasket around the sample entry hole in the card's housing permits areliable fluid-tight seal between a syringe containing sample fluid andthe card. A reliable seal results with little skill required by theoperator to engage the syringe to the card.

All inventive aspects of the diagnostic card of the invention arepreferably accomplished in a substantially flat credit-card sized form.Being flat enables efficient stacking of the cards during their storage,as well as enabling a simple engagement to two coplanar clampingelements in the card reader's card insertion orifice.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described in moredetail by way of example only and with reference to the attacheddrawings, wherein

FIG. 1A is a side view schematic of one preferred embodiment of anelectrode module and sensor membranes in accordance with the invention;

FIG. 1B is a bottom view schematic of another preferred embodiment of anelectrode module in accordance with the invention and showing thepositioning of the metal foil elements;

FIG. 1C is a top view schematic of an electrode module showing thesensor region, the heater region and the contact region of theembodiment of FIG. 1B;

FIG. 2A is a top view schematic of one preferred embodiment of adiagnostic card in accordance with the invention including an electrodemodule and a sealed calibrator fluid chamber with fluidic connections;

FIG. 2B is a side view schematic of the embodiment of FIG. 2A shown incross-section taken along the fluidic path BA^(/) shown in FIG. 2A;

FIG. 2C is a side view schematic of the embodiment of FIG. 2A shown incross-section taken along the fluidic path AA^(/) shown in FIG. 2A, andthe card insertion orifice of the card reader;

FIG. 2D is a side view schematic of the embodiment of FIG. 2A shown incross-section taken along the fluidic path AA^(/) shown in FIG. 2A, andthe partially clamped card insertion orifice of the card reader;

FIG. 2E is a side view schematic of the embodiment of FIG. 2A shown incross-section taken along the fluidic path AA^(/) shown in FIG. 2A, andthe fully clamped card insertion orifice of the card reader;

FIG. 3A is a side view schematic of the electrode module embodiment ofFIG. 2A embedded in the body of the card of FIG. 2A shown incross-section taken along line AA^(/) of the electrode module of FIG.10, and the position of the card reader's heater blocks;

FIG. 3B is a side view schematic of the electrode module embodiment ofFIG. 2A embedded in the body of the card of FIG. 2A shown incross-section taken along BB^(/) of the electrode module of FIG. 10, andthe position of the card reader's heater blocks;

FIG. 4A is a top view schematic of the calibrator fluid chamber andvalve of the card embodiment of FIG. 2A;

FIG. 4B is a side view schematic of the calibrator fluid chamber (beforefluid fill) of the card embodiment of FIG. 2A shown in cross-sectiontaken along AA^(/) shown in FIG. 4A;

FIG. 4C is a side view schematic of the calibrator fluid chamber (afterfluid fill and seal) of the card embodiment of FIG. 2A shown incross-section taken along AA^(/) shown in FIG. 4A; and

FIG. 4D is a side view schematic of the calibrator fluid chamber (afterfluid fill and seal) of the card embodiment of FIG. 2A shown incross-section taken along BB^(/) shown in FIG. 4A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

We describe herein in more detail a preferred embodiment of a diagnosticcard in accordance with the invention, formatted for use with a sensorarray on an electrode module.

FIG. 1A shows a cross-sectional view of an electrode module, fabricatedusing standard smart-card chip-module technology known in the art. Theelectrode module is described in detail in U.S. Pat. Publ. No. US2002/017944 A1, which is incorporated herein by reference. We nowdisclose new inventive features of the module and its use as part of thediagnostic card and card reader.

The module 101 of FIG. 1A comprises an epoxy foil element 102 laminatedto a gold coated copper metal foil 103 with optional adhesive 102A. Theepoxy foil element 102 has through-going holes at 104A and 104B. Themetal foil 103 is formed into an array of electrode elements 130. Theconstruction of the electrode elements will be discussed in thefollowing by way of a pair of electrode elements 130A and 130B. Eachelectrode element 130A and 130B has a connection end 131A, 131B forconnection to a measuring circuit in a card reader (not shown) and asensor end 132A and 132B under the through-going holes in the epoxy 104Aand 104B. The electrode module is received from the vendor on a 35 mmweb. During manufacture, membranes 105A and 105B are applied to themodule on the web extending laterally beyond the perimeter of the holes104A, 104B and overlaying the top epoxy surface, and extending throughthe holes to contact the metal electrodes at the sensor ends 132A and132B. After printing of the membranes, the module is excised from theweb using a die cutter, then placed and sealed into a housing in thediagnostic card as described later. In the preferred embodiment, theexcised module of the FIG. 1 design is about 11 mm square by 120micrometers thickness.

FIG. 1B shows a bottom view (metal foil side) of a module with eightelectrode elements, comprising the laminated epoxy foil 102 and metalfoil 103. This figure shows in more detail the spatial arrangement ofthe metal electrode elements. As in FIG. 1A, two electrodes 130A, 130B,representative of the eight, are labeled to show the relationshipbetween their sensor ends 132A and 132B and their connection ends 131Aand 131B. There is a metal conductor path 133A, 133B between eachelectrode's sensor end 132 and its connection end 131, the path 133Aextending between connector end 131A and sensor end 132A and theconductor path 133B extending between the connector end 131B and sensorend 132B. The metal conductor paths 133 are generally long and thin tominimize lateral heat transport along them when the module is beingheated. Heater contacts 134A, 134B of the metal foil 103 areelectrically isolated from the eight electrode elements. These regionsare for physical contacting by a heater block of the card reader, asdescribed in more detail later.

FIG. 1C shows the module of FIG. 1B in top view (epoxy foil side). Theposition of the electrodes on the underside of the module is shown inthe narrow dashed line. The electrodes are not labeled for reasons ofclarity. Also shown is the position of the through-going holes 104 inthe epoxy relative to the underside metal electrodes. As showndiagrammatically, the layout of the module comprises three distinctregions. The central region of the module is the sensor region 12. Thisregion of the module is proximal to a fluidic conduit in the card whenthe module is assembled into the diagnostic card, as described later.The region proximal to the location of the lower heater block of thecard reader when the card is in the card reader's card insertion orificeis the heater contact region 13. More details of the relationship of theheater blocks of the card reader to the module in the card are givenlater. The region on the periphery of the module where electricalcontact is made by the card reader to the metal electrodes on theunderside of the module is the contact region 14. Those skilled in theart will appreciate that the same standard module fabrication technologycan be used to make modules with many different electrode numbers andgeometries. They differ only in the tooling to provide differentlocations of the through-going holes 104 (see FIGS. 1A and 1B), and themask art-work used to photolithographically define different spatialarrangements of the formed metal elements 103. The general arrangementof any module according to this invention will include a sensor region12 approximately centrally located, a heater contact region 13 at leastpartially adjacent the sensor region, and an electrical contact region14 toward the module's periphery.

FIG. 2A shows a top plan view and FIGS. 2B-E show cross-sectionalschematic views of a preferred embodiment of a diagnostic card inaccordance with the invention, including a sensor array on an electrodemodule, including the card's relationship to elements of the cardreader's card insertion orifice when the card is in the card insertionorifice during the use of the card. FIG. 2B shows one cross-sectionalschematic taken along the fluidic path AA^(/) of FIG. 2A, the fluidicpath extending from a calibrator fluid chamber 220 along a fluidicchannel 210, through the measurement cell 211 to a waste channel 241.FIGS. 2C-E show schematics along the fluidic path BA^(/) of FIG. 2A,being along a fluidic path from the sample entry port 251 through themeasurement cell 211 to the waste channel 241.

Referring to FIGS. 2A and 2B, the diagnostic card in the preferredembodiment is formed from a credit-card sized (85 mm×53 mm×1 mm thick)molded plastic card body 200 with an electrode module 101 as generallydescribed above with reference to FIGS. 1A-1C embedded in the lowersurface of the card body. The electrode module comprises an epoxy foilelement 102 with die-cut through-going passages, the epoxy element beinglaminated with a metal foil that has been formed into eight electrodeelements. Two electrode elements 130A, 130B are shown in FIG. 2B whichhave a sensor end 132A and 132B respectively and a contact end 131A,131B respectively as are shown in the side-view schematic diagram.Membranes 207 and 208 are shown on the top surface of the module andcontacting underside metal elements at the sensor ends 132A and 132Bthrough the passages in the epoxy. The card body 200 also containsmolded features (grooves, trenches and holes) on both its upper (solidlines in the top view schematic) and lower (dotted lines in the top viewschematic) surfaces which molded features, when sealed by otherlaminating elements, form fluidic channels and a sealed fluid reservoir.Laminations are made to the lower and upper surface of the housing bylabel elements 201 and 202 and by metal foil elements 223A and 223B.Elements 201, 202 on the lower and upper surfaces of the card are labelelements die-cut from an adhesive coated polymer sheet. Elements 223Aand 223B are a lamination of two elements which are die-cut from a sheetof metal foil coated with polyethylene for heat sealing.

There are two trenches side by side on the lower surface of the plasticbody. When clad by laminating elements 223A and 223B they form areservoir chamber 220 with a volume of about 150 microliters. There isan orifice 221A through the plastic body 200 through which a calibratorfluid 224 is injected from the upper surface of the body to fill thechamber 220 during card manufacture, with another orifice 222, alsothrough the body 200, for venting of air during the filling process. Thechamber walls are defined by a pair of opposite foil elements 223A and223B made of a plastic coated meal foil. The chamber 220, after fillingwith fluid, is completely sealed when the orifices 221 and 222 areclosed-off during the lamination of foil elements 223A and 223B as isdescribed in more detail later with reference to FIGS. 4B-D.

There is a fluidic channel 210 connecting the calibrator fluid chamber220 to the measurement cell 211at the electrode module's sensor region,and then to a waste channel 241. The diagnostic card also includes asample inlet port 251 which is in fluid communication with a secondchannel 250 connecting the sample inlet port 251 to the measurement cell211. There is a chamber outlet valve 230 for fluidically connecting thecalibrator fluid chamber 220 with the connecting channel 210 between themeasurement cell 211 and the calibrator fluid chamber withoutpressurizing fluid contained within the chamber. This means the valvestructure is operated/operable independent of any pressurization offluid in the chamber. The valve is preferably a rupturing structure forrupturing the wall of the sealed chamber at the connection with theconnecting conduit for fluidically connecting the chamber to theconduit. In this preferred embodiment, the chamber rupturing structureincludes a bore 233 through the body 200 and a rupture element, in thiscase plug 234, located in the bore and within the chamber 220 betweenthe two metal foil elements 223A and 223B. The plug is slightly smallerin diameter than the bore, rendering it capable of axial movementtherein, in this case upwards. The plug 234 is positioned so that aregion of the metal foil element 223A on the peripheral edge of the plug(295 of FIG. 2D) ruptures when the plug is pushed upwards. Any otherstructures useful for the controlled opening of the chamber 200 forconnection with the channel 210 when the card is in the card reader canalso be used to function as the valve 230, as long as they do not leadto a pressurization of the chamber 220 during opening of the chamber.The diagnostic card further includes a delivery structure for forcingfluid from the chamber 220 under pressure, when the chamber containsfluid, and into the connecting conduit 210. In the preferred embodiment,the delivery structure is a portion of the chamber walls which issufficiently flexible to be deformed, preferably from the exterior ofthe card and while the card is inserted in the card reader. Of course,the delivery structure can also be any other structure usable forreliably forcing fluid from the chamber when the chamber is fluidicallyconnected to the connecting conduit.

FIGS. 2C-E schematically show the card in the card orifice of a cardreader (the card reader preferably including a circuit board withdetectors, amplifiers and other circuit components, as described in U.S.Pat. No. 6,845,327 and illustrate the spatial relationship betweenelements of the card and elements of the card-reader's orifice duringuse of the device. In use, the card is first inserted into a cardreader's card insertion orifice (FIG. 2C). The orifice comprises a lowergenerally planar mating element 280 which is co-planar with and proximalto the card's lower surface, and an upper generally planar matingelement 290 which is co-planar with and proximal to the card's uppersurface.

The card reader's card insertion orifice has a guide (not shown) tolocate the features on the card with their respective mating features onthe card reader insertion orifice's planar mating elements during cardinsertion. After insertion, the two mating elements of the card readerinsertion orifice are moved toward each other, thus clamping the cardbetween them. The construction and function of the card reader isdescribed in detail in U.S. Pat. No. 6,845,327, incorporated herein byreference. As the lower surface of the card is brought into contact withthe lower mating element 280 of the card reader's card orifice, a pinelement 282 provided on the mating element 280 first contacts the cardat the calibrator fluid chamber outlet valve 230. The pin 282 pushesplug 234 upwards. This lifts the metal foil laminate above the plugcausing foil 223A to break at location 295 (FIG. 2D), thus fluidicallyopening the calibrator fluid chamber. At the same time, the electrodemodule is electrically contacted by a contacting means of the cardreader which comprises a contacting array of eight metal contactelements formed in a metal film or foil 286 on an insulating flexconnector substrate 287. Two of the eight pins are shown in the sideview schematics of FIG. 2C-E. Each has a contact end 283A, 283B formaking z-action contact to the module's electrode contact locations131A, 131B on the lower surface of the electrode module, and an end284A, 284B for connection to an electrical circuit elsewhere in the cardreader. The flex connector at its module contacting end is mounted onthe movable end of a set of flexible cantilevers 285A and 285B,preferably made of plastic, whose other end is embedded in the lowermating element 280 of the card reader orifice The cantilevers, with theflex connector mounted on it, are in their at-rest position raised abovethe plane of the lower mating element 280 at the location of contact tothe module, so that as the card is clamped to the lower mating elementof the card reader orifice the cantilevers are depressed, thus providingz-action contact force to the electrical contacts made between the flexconnector of the card reader and the electrode module of the card. Atthe same time the card's electrode module is thermally contacted by alower heater block 289 and the top of the diagnostic card above themeasurement chamber by an upper heater block 291. The lower heater block289, which is mounted in the card reader orifice's lower mating element280, makes thermal contact with the module on its lower surface directlyunder the measurement chamber 211, making physical contact to themodule's ‘split ring’ heater contact metal elements 134A, 134B, whilebeing in close proximity to the other metal elements elsewhere on themodule, but electrically isolated from them. At the same time, the upperheater block 291, which is mounted in the card reader orifice's uppermating element, makes thermal contact to the card directly above themeasurement chamber 211. Each heater block contains a heater element anda temperature measuring element each in intimate thermal contact withthe block (not shown). The blocks' heater elements and temperaturemeasuring elements are also connected to the card reader's electricalcircuit. The lower mating element 280 of the card reader also includesan actuator element 281 positioned to be opposite the calibrator fluidchamber 220 when the card is inserted into the card reader's cardorifice. As the card continues to be clamped between the matingsurfaces, the actuator element 281 now engages the delivery structure ofthe calibrator fluid chamber 220, deforming the chamber wall 223 andcompressing the chamber 220, thereby pressurizing the chamber contentsand causing delivery of fluid out of the chamber along fluidic channel210 to measurement chamber 211 (FIG. 2E). When the card is fully clampedin the card reader orifice (FIG. 2E) there is a period of time duringwhich the module, the sensors and the fluid in the measurement cell areheated, preferably to 37.4° C., followed by a period of time duringwhich the module's sensors are calibrated. After this calibrationperiod, the card-reader prompts the user to supply sample fluid to thediagnostic card. The user engages a syringe containing sample fluid tothe card's sample entry port (251 of FIG. 2A and 2B). The syringe tipforms a seal with an adhesive element 253 surrounding the entry port.The sample port 251 may optionally be reversibly sealed with a closureflap which can be part of the label 202. The user delivers sample fluidfrom the syringe to the measurement cell 211 along channel 250, thusdisplacing calibrator fluid out of chamber 211 to waste channel 241. Themodule's sensors now generate sensor signals derived from the samplefluid, which electrical signals are extracted from the electrode modulevia the card reader's electrical flex connector 287 to an electricalcircuit in the reader. After completion of the measurement cycle, thecard is unclamped and withdrawn from the card reader's orifice.

Referring again to FIG. 2, the card is assembled as follows in threeprinciple steps. Step 1: sealing the electrode module 100 to plasticcard body 200. Step 2: forming the metal foil cladding around chamber220 by laminating first lamination 223A and second 223B lamination ofmetal foil elements with insertion of the rupture plug 234 between theselaminations; filling of the clad calibrator chamber 220 with calibratorfluid 224; then sealing calibrator fluid and plug into the clad chamber.Step 3: laminate top 202 and bottom 201 labels. Steps 1 and 2 will nowbe described in more detail.

FIG. 3A and B show in more detail the electrode module assembled intothe plastic card body 200 in step 1 of the assembly process. Referringto FIG. 3A, the molded plastic card body 200, as received from thevendor, is first laminated with the electrode module 100 whose epoxyfoil upper surface 102 faces the card body and is recessed into it andsealed with adhesive 303. The adhesive is applied to the outer area ofthe module's epoxy surface perimetric to the module's central sensorregion. As shown in FIGS. 3A and 3B the adhesive is applied to theentire top epoxy surface, except the sensor region (region 12 shown inFIG. 1C). The module, when embedded in the card, is coplanar with thecard body with the module's upper sensor surface proximal to the cardbody's fluid measurement cell 211 and the module's lower metal surface103 facing the outside.

FIG. 3A and 3B also show in more detail the location of the cardreader's heater blocks relative to the card and its electrode modulewhen the card is clamped in the card reader's card insertion orifice.FIG. 3A shows a cross-section along AA^(/) of the electrode module shownin FIG. 1C, which is in the direction orthogonal to the card's fluidicchannel over the electrode module. FIG. 3B shows a cross-section alongBB^(/) of the electrode module shown in FIG. 1C, which is in thedirection along the path of the card's fluidic channel over theelectrode module. As shown in FIG. 3A, the lower heater block 289physically contacts the electrode module at the locations 134A and 134Bwhich are the electrode module's heater contact metal elements. Thelower heater block 289 is in close proximity to (thus thermallyconnected with) but electrically isolated from, other metal elements ofthe electrode module 100, including the sensor ends 132 and contact ends131 of the electrodes and the metal paths 133 between them. The lowerheater block 289 extends a distance beyond the width of the fluidicmeasurement chamber 211. As shown in FIG. 3B the lower heater block isin close proximity to the metal paths 133 connecting the electrodes'sensor ends 132 to their contact ends 131 but not in physical contactwith them. The upper heater block 291 makes contact to the card's upperplastic label. It too extends beyond the width of the measurementchamber 211 (FIG. 3A), but also extends a distance along the fluidicchannel beyond the electrode module on both sides (FIG. 3B). We havefound that when the upper heater extends about 5 mm beyond the modulethere is satisfactory thermal bootstrapping of the fluid beyond thesensor region of the module, thus assuring excellent thermal control ofthe temperature of the sensor region.

We have found that when the card is fully clamped in the card reader'sorifice, at which time the lower heater block 289 contacts the electrodemodule's heater contacts 134, the regions of the heater block not incontact with, but in proximity to the module, should be spaced about 25micrometers from the module's metal surface. At this distance there isstill satisfactory heat transfer from heater block to module, but thereis also reliable electrical isolation during repeated use of the cardreader. In general, the rate of heat transfer from the heater block tothe module increases with decreasing spacing. The preferred range ofspacing is 10 to 50 micrometers. However, the person skilled in the artwill appreciate that a spacing below 10 micrometers may be usable aslong as reliable electrical insulation of the heater block from thesensing and contacting regions of the module is ensured. A spacing above50 micrometers is usable, but the heat transfer rate will be low.

FIG. 4 shows in more detail the metal foil clad calibrator fluid chamber220 and the foil rupturing plug, and its forming, filling and sealingprocesses which together are step 2 of the card assembly procedure.Referring to FIG. 4A which is a top view schematic of the card'scalibrator fluid reservoir region and FIG. 4B which is a cross-sectionthrough the embodiment of FIG. 4A taken along line AA^(/), being alongthe fluidic path from the calibrator fluid fill hole 221 along thecalibrator fluid reservoir 220, its connecting channel 405 to the venthole 222. The card body 200 in the calibrator fluid reservoir region ofthe card features a molded calibrator fluid reservoir cavity 401 (shownhere as two parallel cavities fluidically connected), a molded trench405 connecting the cavity 401 to a rupture-plug bore 233 and a secondtrench 210 connecting the rupture-plug bore to the measurement cell 211(see FIG. 2A). A first metal foil element 223A has a pressure sensitiveadhesive on one side of the metal and approximately 25 micrometersthickness polyethylene coating on the other. The element 223A, which isdie cut from a sheet and placed with its adhesive side down onto thecard body, extends over the calibrator fluid reservoir cavity 401, theconnecting channel 405 and the rupture-plug bore 233, overlaying allthese features and extending to a perimeter beyond them. When high airpressure is applied to the foil element 223A it deforms taking thecontour of the card body's reservoir cavity 401, connecting channel 405and rupture-plug hole 233, being then attached to the body's surface bythe pressure sensitive adhesive. The polyethylene coated surface of foilelement 223A faces the inside of the reservoir cavity. The foildeforming procedure is similar to the blow-molding process well known inthe art. In manufacture, a tool with an air pressurizable cavity isengaged to the foil on the card body and sealed to it about the cavity,preferably by an elastomeric gasket. When high pressure air isintroduced into the tool's cavity, the air blow-deforms the metal foilto take the contour of the card body. It will be readily apparent to theperson skilled in the art that other methods of shaping the foil element223A to take on the contour of the card body may also be used, such ashydroforming. A rupture-plug element 234, which is a rigid discapproximately the same thickness as the card body with a diametersomewhat smaller than the diameter of the rupture-plug bore 233, isplaced onto the foil element 223A in the depression in the foil formedover the rupture-plug bore 233. The foil element 223A is pierced at thebottom of fluid fill hole 221 and vent hole 222. A second polyethylenecoated metal foil element 223B is laminated over the first foil element223A with its polyethylene coating facing the polyethylene coating ofelement 223A. A heat seal is made between foil elements 223A and 223B,by fusing the two polyethylene coating layers, everywhere except in thefill and vent regions 415 and 416 adjacent the fluid fill and vent holes221 and 222 respectively. At this stage, the foil clad calibrator fluidreservoir is sealed except for the fill and vent holes 221, 222 as shownin FIG. 4B and is now ready to receive fluid. Calibrator fluid 224 isintroduced through fill hole 221 into chamber 220 filling it andpartially filling the channel 405 while expelling air from the chamberthrough vent hole 222. In the final step, once the chamber 220 isfilled, the fill and vent regions 415 and 416 near the fill and ventholes 221, 222 are then sealed in a secondary heat seal process, thusentirely sealing the calibrator fluid and rupture plug within the twofoil elements as shown in FIGS. 4C and 4D. Lamination of the card body200 with an upper pressure sensitive adhesive coated label element 202now forms a channel 210 which fluidically connects the region 450 of thecalibrator chamber where the rupture of the foil takes place (FIG. 4D)with the measurement cell 211 (see FIG. 2A). A second lower labellamination 201, which leaves the lower surface of the electrode module100 exposed, completes the card assembly.

Using the above recited fluid chamber design and manufacturing procedurewe have achieved a remarkably long period of calibrator fluid storagestability. The mean time to failure of a sealed fluid used for sensorcalibration is the time for the carbon dioxide partial pressure to dropfrom its initial value in the fluid to an unacceptably low level as thegas permeates out through the heat fused polyethylene seam. We havefound that we can achieve greater than 6 months room temperature storagestability in which time the partial pressure of carbon dioxide changesfrom its average value by less than 0.5 mm Hg. To achieve this we havedesigned the perimeter seal width to be greater than 3 mm width at alllocations along the perimeter. This high level of stability is in markedcontrast to other devices of the known art, which must be stored in therefrigerator to achieve extended lifetime. Using the above recited fluidchamber design with incorporated rupture plug we have achieved a simplefoil rupturing method which opens the foil-sealed chamber during the useof the device, but before the calibrator fluid in the chamber ispressurized to expel it from the chamber and to the measurement cell.This achieves a high level of reliability and control in the calibratorfluid delivery step of the device's operation.

Those skilled in the art will recognize that the various inventiveelements of the diagnostic card can be used together as they are in thecard of this disclosure, or they can be used separately in differentcard designs. For example, the sealed fluid chamber and its valvestructure means can be incorporated into diagnostic cards comprisingmicro-porous fluidic elements such as those as disclosed in U.S. Pat.No. 7,722,817. In this case the sealed fluid is used for priming themicro-porous pump elements rather than for sensor calibration purposes.The inventive fluidic arrangements and sealed fluid chamber can beadvantageously used with electrode modules comprising foil laminates asdescribed in this disclosure, but they can also be used with sensormodules of other kinds, including the many types of sensor modules ofthe known art which are fabricated on a planar insulating substrates(microfabricated chips, planar circuit boards and the like) andincluding sensor modules incorporating non-electrochemical sensing meanssuch as optical, chemiluminescence or fluorescence, as are known in theart. Indeed, these inventive fluidic components will be useful in anyunit-use diagnostic card incorporating an on-board fluid.

The above-described embodiments of the present invention are intended tobe examples only. Alterations, modifications and variations may beeffected to the particular embodiments by those of skill in the artwithout departing from the scope of the invention, which is definedsolely by the claims appended hereto.

What is claimed is:
 1. A method of forming a sealed fluid reservoir in adiagnostic card, comprising the steps of obtaining a diagnostic cardbody with a reservoir recess in a surface of the card body; lining therecess with a first laminate of a plastic film layer and an aluminumfoil layer, the foil layer contacting the card body and the firstlaminate extending beyond the recess; placing a second laminate of aplastic film layer and an aluminum foil layer over the first laminate sothat the plastic film layers contact one another; and forming a sealedreservoir by heat bonding the film layers along a periphery of the firstand second laminates forming a continuous heat bond line.
 2. The methodof claim 1, wherein the first laminate is pressure formed into therecess to closely follow a contour of the recess.
 3. The method of claim1, wherein the heat bond line has a minimum transverse width of 3 mm. 4.The method of claim 1, wherein the recess includes a filler passage anda vent passage and the method includes the additional steps ofperforating the first laminate over the filler and vent passages to formfiller and vent openings therein, filling the sealed reservoir afterheat bonding of the film layers by injecting fluid through the filleropening, and sealing the reservoir by forming a second heat bond of thefilm layers about the filler and vent openings.
 5. The method of claim2, comprising the further step of, prior to placement of the secondlaminate, placing a rupture plug on the first laminate at a desiredlocation of rupture so that the rupture plug is contained in thereservoir after heat bonding of the film layers.
 6. The method of claim5, wherein the card body includes a plug receiving bore, the firstlaminate is pressure formed into the recess to closely follow a contourof the recess and the plug receiving bore, the plug is shaped and sizedto slidably fit into the plug receiving bore, and the plug is placed atthe location of the plug receiving bore prior to placement of the secondlaminate.
 7. A diagnostic card reader for use with a diagnostic cardhaving substantially planar opposite first and second surfaces, ameasuring region and an electrode module located in the measuring regionand having a conductor layer exposed in the first surface, the conductorlayer being divided into a substantially central sensing region, asubstantially peripheral contacting region including electrode contactends, and an intermediate heating region surrounding the sensing regionand including a heater contact element, the card reader comprising: ahousing; a card cavity for receiving at least a portion of thediagnostic card to locate the conductor layer of the electrode moduleinside the card cavity; a contacting arrangement for electricallycontacting at least one of the electrode contact ends of the electrodemodule when the card is received in the card cavity; and a first heaterblock for heating the sensing region of the electrode module when thecard is received in the card cavity, the heater block having a firstblock portion for physically contacting the heater contact element ofthe electrode module and heating the heating region by direct thermalconduction, and a second block portion backset from the first portion tobe spaced apart parallel to the sensing region of the electrode modulewhen the first block portion is in physical contact with the heatercontact element for heating the sensing region by indirect thermaltransfer.
 8. The card reader of claim 7, wherein the contactingarrangement includes at least one metal contacting element in the formof a formed metal film carried on a flex substrate mounted on a flexiblesupport in the card reader's card insertion orifice for resilientlycontacting the contact end when the card is received in the card cavity.9. The card reader as defined in claim 7, further comprising a secondheater block for physically contacting the second surface of the card inthe measuring region for heating at least the portion of the measuringregion which coincides with the sensing region of the card and forheating any liquid within the card in the measuring region.
 10. The cardreader as defined in claim 9, wherein the heater block extends beyondthe measuring region for heating fluid in any conduits in the cardleading to and from the measuring region.